Buckling behavior of fiber reinforced Innegra sandwich beams incorporating carbon nanofiber

This study examined the effect of carbon nanofiber (CNF) on the buckling behavior of sandwich beams under axial compressive load. Three different configurations of sandwich beams consisting of composite skins with different arrangement of layers and polyvinyl chloride (PVC) foam core were considered. Each composite skin is made of four layers reinforced with different materials consisting of Innegra, carbon and Innegra/carbon (hybrid) and epoxy resin modified by CNF. Because of the difference in the thickness of the samples, the specific critical load parameter (the ratio of the critical buckling load to the thickness of the structure) was used to compare the buckling behavior of sandwich beams. The experimental test results indicated that carbon fiber as a stiffening interface in hybrid samples improved the specific critical load compared to Innegra samples. Also, the addition of 0.3 wt%-CNF increases the specific critical load, while the further increase of CNF led to the decrease of the specific critical loads, which is the main cause of weak interfacial stress between CNF and epoxy resin. In addition, the effect of different percentages of CNF and types of fibers on the increase in toughness and damage mechanisms were investigated.